Methods for improving uplink (UL) coverage, throughput and transmission latency are being investigated in Release 6 (R6) of the 3rd Generation Partnership Project (3GPP). In order to successfully implement these methods, the scheduling and assigning of UL radio resources have been moved from an RNC to a Node-B such that the Node-B can make decisions and manage UL radio resources on a short-term basis more efficiently than the RNC, even if the RNC retains overall control over the Node-B.
In order for a WTRU to transmit data over an E-DCH, the WTRU needs to transmit E-DCH channel allocation requests to the Node-B via a UL EU signaling channel. Then, the Node-B determines the proper allocation of physical resources for the WTRU and transmits the scheduling information via the downlink (DL) EU signaling channel. After the radio resources are allocated to the WTRU, the WTRU transmits data through the E-DCH. The Node-B receives the data and determines success or failure of the E-DCH transmission. The Node-B signals the success or failure of the transmission to the WTRU through the DL EU signaling channel.
In order for the E-DCH to work properly, both UL and DL EU signaling channels have to be reliable. When either the UL or DL EU signaling channel is not working properly, it should be reported to the RNC to provide proper EU operation.